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Research On LAMOST Fiber Position Detection Based On "Front Shot Method"

Posted on:2021-05-17Degree:MasterType:Thesis
Country:ChinaCandidate:Y ShengFull Text:PDF
GTID:2428330602999019Subject:Instrument Science and Technology
Abstract/Summary:PDF Full Text Request
The entire system of LAMOST requires high positioning accuracy of the fiber positioning unit.Some units are difficult to reach the accuracy range of 40 microns at one time.some units to achieve accurate positioning accuracy at one time.It is necessary to quickly detect the gap between the current position of the fiber and the target position through a high-precision measurement system and pass the control of the closed loop system,Let the fiber unit perform multi-wheel positioning to meet the system's requirements for the positioning accuracy of the fiber positioning unit.In addition,due to possible motor failures and other factors,it is necessary to detect the position of the optical fiber to find out the faulty optical fiber unit and replace it to ensure the stable and continuous operation of LAMOST.This paper mainly studies the fiber position detection algorithm based on the"front-illumination method".With the continuous improvement of the resolution and accuracy of the shooting camera,the front-end illumination method is used to capture the focal plane image of the fiber,and the "front-illumination algorithm" is used to extract the fiber unit in the picture.Pixel coordinates.The designed "front-illumination algorithm" process is mainly divided into three parts.The first part mainly reads the CMOS camera to take pictures through image preprocessing,uses median filtering and top-hat and bottom-hat transformation to eliminate interference noise and uneven illumination.And through the binarization processing and edge detection to obtain the edge binary image of the captured image;the second part uses the radius-based Hough algorithm to search the fiber spot to be detected,remove useless interference contours,and perform rough extraction of the fiber unit contour;third Partly extract the outline of the optical fiber spot,using least square method to accurately fit the pixel coordinates of the optical fiber,and improve the accuracy of optical fiber position detection.According to the "front-illumination method" fiber position detection algorithm flow designed in this paper,theoretical research and analysis are carried out,and the current conditions and design of the "front-illumination method" algorithm flow are analyzed for the theoretical accuracy and feasibility of extracting fiber pixel coordinates through simulation simulation experiments.Sex.The stability experiment of continuous shooting was carried out to observe the stability of the shooting results.The leaking and misrecognition of the optical fiber unit in the actual shooting was further optimized with the front-lighting algorithm to achieve accurate identification of the optical fiber unit under laboratory conditions.The stability results of the continuous shooting experiment are calculated and optimized,so that the theoretical accuracy and stability of the "front shot method" are within 0.1 pixel.Finally introduced into the actual shooting environment and observe the shooting results.
Keywords/Search Tags:LAMOST, front illumination method, Hough transform, least squares method, circle-center fitting
PDF Full Text Request
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